A color filter method and a field sequential method are known as display methods for liquid crystal display devices. In a color-filter liquid crystal display device, a plurality of subpixels which has color filters each transmitting only light having wavelengths exhibiting a given color (e.g., red (R), green (G), or blue (B)) are provided in each pixel. A desired color is expressed in such a manner that transmission of white light is controlled in each subpixel and a plurality of colors is mixed in each pixel. On the other hand, in a field-sequential liquid crystal display device, a plurality of light sources that emits light of different colors (e.g., red (R), green (G), and blue (B)) is provided. A desired color is expressed by sequential light emission of the plurality of light sources that emit light of different colors and control of transmission of light of different colors in each pixel.
A field sequential method has the following advantages over a color filter method. First, in a field-sequential liquid crystal display device, it is not necessary to provide subpixels in each pixel. Thus, the aperture ratio can be improved or the number of pixels can be increased. In addition, in a field-sequential liquid crystal display device, it is not necessary to provide a color filter, which leads to no loss of light due to absorption of light by a color filter. Thus, in the case of such a field-sequential liquid crystal display device, transmittance can be increased and power consumption can be reduced.
Patent Document 1 discloses a field-sequential liquid crystal display device. Specifically, Patent Document 1 discloses a liquid crystal display device in which each pixel includes a transistor that controls input of a video signal, a signal storage capacitor that stores the video signal, and a transistor that controls transfer of charge from the signal storage capacitor to a display pixel capacitor. In the liquid crystal display device having this structure, input of a video signal to the signal storage capacitor and display corresponding to charge held in the display pixel capacitor can be performed at the same time.